He did rule out terrorism in the fiery wreck that has claimed at least 15 lives.

Investigators have said they are trying to figure out whether the oil train's brakes were disabled before it barreled into the small town of Lac-Megantic early Saturday, causing a massive fireball to tear through downtown.

Ed Burkhardt, head of the Montreal, Maine & Atlantic Railway, blamed those firefighters for the derailment, telling media outlets there's evidence the engine powering the brakes was shut down at some point.

The news comes as officials began allowing some of the 1,200 Lac-Megantic residents evacuated by the explosion back to their homes, the Montreal Gazette reported.

About three dozen people remained missing Tuesday, with authorities saying some victims were likely vaporized by the intense blaze that burned for 36 hours after the crash.